Figure 4.

Electrophysiological analysis of inaF^P106x in comparison to trp mutants. (A) Effects of inaF^P106x mutation on the TRP (a) and TRPL (b) channel responses. (a) The receptor potentials recorded from the double mutants inaF^P106x;trpl³⁰², trpl³⁰²;trp^P301, and trpl³⁰²;trp^P343 are compared with that of trpl³⁰². The peak amplitudes of the inaF^P106x;trpl³⁰², trpl³⁰²;trp^P301, and trpl³⁰² responses are, respectively, 13.1 ± 3.3, 10.3 ± 1.9, and 27 ± 3.6 mV. (b) The receptor potential recorded from trp^P343 is compared with that from the double mutant inaF^P106x;;trp^P343. The wild-type response is as shown in Fig. 1. White light stimuli (20 s) were used throughout. (B) Refractory properties of the residual TRP responses of the double mutants, inaF^P106x;trpl³⁰² and trpl³⁰²;trp^P301. Two successive stimuli (S1 and S2) separated by a 20-s interval (top trace) are presented to trpl³⁰² (a), inaF^P106x;trpl³⁰² (b), and trpl³⁰²;trp^P301 (c) following 2-min dark adaptation, and the resulting responses (R1 and R2) for each genotype are compared by superimposing. Control responses obtained from inaF^P106x and trp^P301 by using the same protocol are shown in d and e. The stimuli are white light of 2-s duration filtered with a 1-log-unit neutral density filter.